Thread Navigating by Arrow keys

Use ← or → and Ctrl to navigate to previous, next, first or last page
Versión del día 13/05/2017. Echa un vistazo a la versión más reciente.
Pregunta tus dudas, ponle nota o notifica una posible infracción de las normas.
Ajuste de línea
// ==UserScript==
// @name        Thread Navigating by Arrow keys
// @namespace   https://greasyfork.org/scripts/6849-thread-navigating-by-arrow-keys
// @description Use ← or → and Ctrl to navigate to previous, next, first or last page
// @author      theheroofvn
// @include     /^.*(thread|forum|diendan).*$/
// @include     http://www.vn-zoom.com/*
// @require     http://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js
// @noframes
// @grant       GM_addStyle
// @version     6.1
// ==/UserScript==

$(document).ready(function () {
    $(window).focus();

    function custom_site(list) {
        if (list.length === 0) return 0;
        for (var i = 0; i < list.length; i++) {
            if (location.hostname == list[i].host) {
                prev = list[i].prev;
                next = list[i].next;
                first = list[i].first;
                last = list[i].last;
                up = list[i].up;
                return 1;
            }
        }
        return 0;
    }

    function checkScriptExist(script) {
        return $('script[src*="' + script + '"]').length > 0 ? true : false;
    }

    function detect_forum() {
        var result = "";
        if (checkScriptExist("vbulletin")) result = "vbb";
        else if (checkScriptExist("xenforo")) result = "xenforo";
        else if (checkScriptExist("general.js")) result = "mybb";
        else if (checkScriptExist("forum_fn.js")) result = "phpbb";
        return result;
    }

    var prev, next, first, last, up, up_sub = '[itemtype="http://data-vocabulary.org/Breadcrumb"] a';
    var site_info = [{
        host: "www.webtretho.com",
        prev: "a.arrowPrePage",
        next: "a.arrowNextPage",
        first: "a.arrowFstPage",
        last: "a.arrowLstPage"
    }, {
        host: "forum.bkav.com.vn",
        prev: "a.js-pagenav-prev-button",
        next: "a.js-pagenav-next-button",
        first: "a[data-page='1']",
        last: "a.js-pagenav-button:nth-last-child(2)",
        up: "#breadcrumbs a.crumb-link"
    }];

    if (custom_site(site_info) === 0) {
        switch (detect_forum()) {
            case 'vbb':
                prev = 'a[rel="prev"]';
                next = 'a[rel="next"]';
                first = 'a[rel="start"]';
                last = 'a[title^="Last"], a[title*="uối"]';
                up = "span.navbar a, li.navbit a";
                break;
            case 'xenforo':
                prev = ".PageNav a.text:first-child";
                next = ".PageNav a.text:last-child";
                last = ".PageNav nav > a:nth-last-child(2)";
                first = 'a[rel="start"]';
                up = "a.crumb";
                break;
            case 'mybb':
                prev = "a.pagination_previous";
                next = "a.pagination_next";
                first = "a.pagination_first";
                last = "a.pagination_last";
                up = ".navigation > a";
                break;
            case 'phpbb':
                prev = ".display-options a.left-box.left";
                next = ".display-options a.right-box.right";
                first = ".pagination > span > a:first-child";
                last = ".pagination > span > a:last-child";
                up = ".navlinks > .icon-home a";
                break;
            default:
                return;
                break;
        }
    }

    var nav = {
        prev: $(prev),

        next: $(next),

        first: function () {
            if ($(first).length > 0) {
                return $(first);
            } else {
                let $prev = $(prev).first();

                if ($prev) {
                    $prev.attr('href', function (_, value) {
                        return value.replace(/page=\d+/, 'page=1');
                    });

                    return $prev;
                } else {
                    return $();
                }
            }
        },

        last: function () {
            if ($(last).length > 0) {
                return $(last);
            } else {
                let $next = $(next).first();

                if ($next) {
                    $next.attr('href', function (_, value) {
                        return value.replace(/page=\d+/, 'page=9999');
                    });

                    return $next;
                } else {
                    return $();
                }
            }
        },

        up: function () {
            return $(up).length > 0 ? $(up).last() : $(up_sub).last();
        }
    };

    var allowed = true;

    $(document).keydown(function (e) {
        if (!allowed) {
            return;
        }

        allowed = false;

        var key = e.keyCode,
            action = null;

        if (e.ctrlKey) {
            allowed = true;
            if (key == 39) action = "last";
            else if (key == 37) action = "first";
            else if (key == 8) action = "up";
        } else if (key == 39) {
            action = "next";
        } else if (key == 37) {
            action = "prev";
        } else {
            return;
        }

        if (!action || e.target.tagName == "INPUT" || e.target.tagName == "TEXTAREA") {
            return;
        }

        var $anchor = (typeof nav[action] === "function") ? nav[action]() : nav[action];

        if ($anchor.length) {
            window.location = $anchor.attr('href');
        }
    }).keyup(function (e) {
        allowed = true;
    });
});